This application claims benefit of Japanese Application No. Hei 11-137735 filed in Japan on May 18, 1999, the contents of which are incorporated by this reference.
1. Field of the Invention
This invention relates to an optical system, more particularly to an optical system which leads images of a display element into eye balls of a viewer by way of a plurality of prisms.
2. Related Art Statement
Recently, head-mounting type video display devices which enable viewers to enjoy video and sound while mounting the devices on their heads have been commercialized. For example, the devices are mounted in a manner similar to mounting of glasses and the viewers can observe a large screen video.
In such a head-mounting type video display device, images are displayed by a small-sized LCD or the like and the images are enlarged by way of an optical system and are projected to eye balls of the viewer. Considering the mounting mode that the device is mounted on the head, efforts have been made so as to make the optical system have a compact constitution and a high performance.
As an example of such an optical system, Japanese Laid-Open Publication 333551/1995 discloses a viewing optical system formed of a single prism wherein images displayed by an LCD or the like are reflected on a plurality of reflection surfaces including a full reflection surface and a reflection surface formed of a curved surface having an optical power so as to lead images to eye balls of a viewer.
Further, Japanese Laid-Open Publication 73005/1997 discloses a technique which protrudes positioning portions from, for example, both side faces of a prism element having a plurality of reflection surfaces and the prism element is accurately positioned and fixedly secured to other member by means of shaped portions formed on these positioning portions. The publication also discloses a technique where a second optical element which transmits an outside scenery to eye balls of a viewer is combined with a first optical element which leads images displayed by display means such as an LCD or the like into the eye balls of the viewer.
With respect to devices disclosed in the above-mentioned Japanese Laid-Open Publication 333551/1995 and Japanese Laid-Open Publication 73005/1997, the optical element which leads the images displayed by the display element such as the LCD or the like is formed of a single prism. However, recently, high pixels and high definition of the display element have been requested. To realize such a display element having such a high definition, the use of the optical system which leads images to eye balls of the viewer only with the single prism is not necessarily optimal and hence, there arises a necessity to take into account an optical system constituted by combining a plurality of prisms. In this case, the relative positional relationship between these prisms must be determined with a high precision and hence, the realization of a technique which satisfies such a demand is requested.
It is an object of this invention to provide an optical system which can position a plurality of prisms with a high accuracy.
To summarize this invention, the optical system of this invention is an optical system which forms images on an eye ball of a viewer such that the viewer can observe images of a display element and includes a first prism which has first connecting portions and allows light beams from the display element to pass therethrough and a second prism which has second connecting portions and allows beams projected from the first prism to pass therethrough, and the first connecting portions and the second connecting portions are joined and aligned or registered with each other by way of joining portions formed on a mirror frame which fixedly secures the display element thereto.
Further, this invention is directed to an optical system which forms images on an eye ball of a viewer such that the viewer can observe images of a display element, wherein the optical system includes a first prism which has first connecting portions and allows light beams from the display element to pass therethrough and a second prism which has second connecting portions and allows beams projected from the first prism to pass therethrough, and the first prism and the second prism are aligned or registered with each other by joining the first connecting portions and the second connecting portions.
Further, this invention is directed to an optical system which forms images on an eye ball of a viewer such that the viewer can observe images of a display element, wherein the optical system includes a first prism which allows light beams from the display element to pass therethrough and a second prism which allows beams projected from the first prism to pass therethrough, and the first prism and the second prism are formed by an integral molding by, way of the connecting portions.
Further, this invention is directed to an optical system which enables an observation by superposing images of a display element and images of an outer field, wherein an image forming optical system is constituted by having a plurality of surfaces which reflect light, and includes a prism which has at least a portion of at least one surface out of a plurality of these surfaces formed of a half mirror (semi-transparent mirror) surface and an optical member for observing the images of the outer field which is formed on the half mirror surface by a composite molding.
Further, this invention is directed to an optical system which forms images such that images of a display element can be observed, wherein the optical system includes a first prism which has a projection surface through which incident light beams from the display element are projected after passing through the inside of the first prism, a second prism which includes an incidence surface through which light beams projected from the first prism enters, and connecting portions which connect the first prism and the second prism such that the first prism and the second prism are arranged with a given positional relationship.
These objects and advantages of this invention will become further apparent from the following detailed explanation.